Controlling Access to Files

Oracle Solaris is a multiuser environment. In a multiuser environment, all the users
who are logged in to a system can read files that belong
to other users. With the appropriate file permissions, users can also use files
that belong to other users. For more discussion, see Chapter 6, Controlling Access to Files (Tasks). For step-by-step instructions on
setting appropriate permissions on files, see Protecting Files (Task Map).

Protecting Files With Encryption

You can keep a file secure by making the file inaccessible to
other users. For example, a file with permissions of 600 cannot be read except
by its owner and by superuser. A directory with permissions of 700 is
similarly inaccessible. However, someone who guesses your password or who discovers the root
password can access that file. Also, the otherwise inaccessible file is preserved on a
backup tape every time that the system files are backed up to
offline media.

Sharing Files Across Machines

A network file server can control which files are available for sharing. A
network file server can also control which clients have access to the files,
and what type of access is permitted for those clients. In general, the
file server can grant read-write access or read-only access either to all clients
or to specific clients. Access control is specified when resources are made available
with the share command.

Restricting root Access to Shared Files

In general, superuser is not allowed root access to file systems that are
shared across the network. The NFS system prevents root access to mounted
file systems by changing the user of the requester to the user nobody
with the user ID 60001. The access rights of user nobody are the
same as those access rights that are given to the public. The user
nobody has the access rights of a user without credentials. For example, if
the public has only execute permission for a file, then user nobody can only
execute that file.